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Tuesday, 24 April 2012

Manufacturing: Nature-inspired, 3D-Printed

EngineerbloggerApril 24, 2012

Urbee with its completed 3D-printed body. Image: KOR EcoLogic Inc.

The first 3D-printed car body may set the pace for a new mode of manufacturing.

3D printing is a transformational technology. Originally used exclusively by engineering departments for verifying prototype designs, 3D printing is now being considered for mass production. Think of it as taking the mature technology of 2D digital printing, which reduced the role of the printing press, and carrying that digitizing idea into the third dimension.

Products, including a remote-control model airplane, a bikini, a titanium jaw bone, a bicycle, and a car body have been designed exclusively for the 3D printing process and manufactured on demand. These sophisticated designs were 3D printed because the 3D manufacturing process places the particles of material exactly where they are needed.

KOR EcoLogic Inc., Manitoba, Canada, has engineered a 3D-printed car body. The car project, called Urbee, began 15 years ago, spawned by the company's concern for the escalating global use of fossil fuels. The company's product designers wanted to act as catalysts for change and took a scientific approach to the redesign of the automobile. The designers believed a return to fundamentals and an emphasis on energy efficiency, were the keys to sustainability. The goal was to design the greenest car possible. The approach was to reduce the required energy low enough to power a practical car solely on renewable energy. The car that emerged from this novel approach was named Urbee, for Urban Electric.

The design element of Urbee that received the most attention was how 3D printing was used to fabricate the car's acrylonitrile butadiene styrene (ABS) plastic body. Previously, 3D printing was not considered suitable for body panels this large—finished panels measuring about 5 feet wide, 3 feet high, and 5 feet long, were made by dovetail joining four parts; each of the four parts were 3D printed.

The large parts were made for the vehicle with help from 3D printer manufacturer Stratasys (Eden Prairie, Minn.), CAD software developers Tebis (Troy, Mich.) and Autodesk (San Rafael, Calif.), simulation software provider CD-Adapco, and others. During this development program, the team became aware that this manufacturing process has significant potential for producing extremely light, strong, and environmentally benign structures.

The designers saw parallels between the honeycomb structure of beehives and 3D printing. They believe only the 3D printing process can create structures as sophisticated as found in nature; and can do so by using non-toxic materials and incorporating intelligence from human brains and electronic computers. The employment of simulation programs using high-performance computing (HPC), and 3D printing's unique ability to mass produce any result from these computers, is presenting new possibilities in product design.

Using HPC, a computer model can virtually test thousands or even millions of alternatives for optimal material composition, shape, and production process. Testing just a fraction of these options with physical prototypes would be prohibitively expensive. Although the modeling is feasible on a high-end PC, it would take too long. HPC allows a very large number of scenarios to be modeled accurately and quickly; the first physical prototype comes very close to the design specifications. For example, a small company currently is using HPC to design custom alloys for the aerospace industry, achieving superior mechanical performance, lower production costs, and replacing rare-earth materials with less expensive and more benign materials. HPC has even been used to analyze biosphere designs to understand how they achieve their structural performance.

Light and strong structures are currently being made primarily by the use of tooling and, at times, use of toxic materials. These materials and fabrication techniques are typically considered a necessity for mass production and for proper economies of scale. Although apparently efficient in the short run, these methods may prove quite uneconomic and problematic over any longer view.

The Urbee team plans to design and build a second Urbee prototype. This second car further explores the potential of 3D printing. All exterior and interior panels will be optimized and made on a Stratasys Fortus 3D printer. All of these strong, lightweight body and interior panels will integrate many functional requirements, such as ducting and wiring, while tightly encasing a tubular metal chassis and hybrid power train. All panels will be printed individually, one particle at a time, without need for any hard tooling.